When a stabilizer for a protein formulation is needed to protect a protein from denaturation upon shaking, agitation, shearing and freeze thaw, or in quiescent state at interface, a nonionic detergent (i.e., a surfactant) is often used (see, e.g., U.S. Pat. No. 5,183,746). This is exemplified by the use of polysorbates in many protein-containing products. For example, polysorbates 20 and 80 (Tween® 20 and Tween® 80) are used in the formulation of biotherapeutic products for both preventing surface adsorption and as stabilizers against protein aggregation (Kerwin, J. Pharm. Sci. 97(8):2924-2936 (2008)). The polysorbates are amphipathic, nonionic surfactants composed of fatty acid esters of polyoxyethylene (POE) sorbitan, being polyoxyethylene sorbitan monolaurate for polysorbate 20 and polyoxyethylene sorbitan monooleate for polysorbate 80.
Unfortunately, however, polysorbates can undergo degradation via either oxidation or hydrolysis. When a polysorbate molecule degrades, it generates various degradation byproducts including, for example, fatty acids, POE sorbitan, PEG, PEG esters and alkyl acids. Certain of these byproducts of polysorbate degradation, including the free fatty acids, can cause increased turbidity of and protein aggregation in protein-containing formulations. Therefore, while polysorbates are commonly used as protein stabilizers, the fatty acids and other degradation byproducts released from polysorbate degradation over time can adversely impact the protective effect that polysorbates exhibit in protein-containing formulations.
Proteins undergo varying degrees of degradation during purification and storage, wherein oxidation (including, light-induced oxidation) is one of the major degradation pathways that has a destructive effect on protein stability and potency. Oxidative reactions cause destruction of amino acid residues, peptide bond hydrolysis, and hence protein instability due to alteration of the protein's tertiary structure and protein aggregation (Davies, J. Biol. Chem. 262: 9895-901 (1987)). Oxidation of protein pharmaceuticals have been reviewed by Nguyen (Chapter 4 in Formulation and Delivery of Protein and Peptides (1994)), Hovorka, (J. Pharm Sci. 90:25369 (2001)) and Li (Biotech Bioengineering 48:490-500 (1995)).
Given the above, it is evident that there is a need for the identification of compositions useful for enhancing the stability and preventing the aggregation and/or oxidation of proteins in protein-containing formulations.